diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 4995c078cff98..3556637768fd5 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -409,7 +409,19 @@ static bool rcu_is_gp_kthread_starving(unsigned long *jp) static bool rcu_is_rcuc_kthread_starving(struct rcu_data *rdp, unsigned long *jp) { - unsigned long j = jiffies - READ_ONCE(rdp->rcuc_activity); + int cpu; + struct task_struct *rcuc; + unsigned long j; + + rcuc = rdp->rcu_cpu_kthread_task; + if (!rcuc) + return false; + + cpu = task_cpu(rcuc); + if (cpu_is_offline(cpu) || idle_cpu(cpu)) + return false; + + j = jiffies - READ_ONCE(rdp->rcuc_activity); if (jp) *jp = j; @@ -434,6 +446,9 @@ static void print_cpu_stall_info(int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); char *ticks_title; unsigned long ticks_value; + bool rcuc_starved; + unsigned long j; + char buf[32]; /* * We could be printing a lot while holding a spinlock. Avoid @@ -451,7 +466,10 @@ static void print_cpu_stall_info(int cpu) delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq); falsepositive = rcu_is_gp_kthread_starving(NULL) && rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)); - pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld %s\n", + rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j); + if (rcuc_starved) + sprintf(buf, " rcuc=%ld jiffies(starved)", j); + pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld%s%s\n", cpu, "O."[!!cpu_online(cpu)], "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)], @@ -464,32 +482,10 @@ static void print_cpu_stall_info(int cpu) rdp->dynticks_nesting, rdp->dynticks_nmi_nesting, rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, + rcuc_starved ? buf : "", falsepositive ? " (false positive?)" : ""); } -static void rcuc_kthread_dump(struct rcu_data *rdp) -{ - int cpu; - unsigned long j; - struct task_struct *rcuc; - - rcuc = rdp->rcu_cpu_kthread_task; - if (!rcuc) - return; - - cpu = task_cpu(rcuc); - if (cpu_is_offline(cpu) || idle_cpu(cpu)) - return; - - if (!rcu_is_rcuc_kthread_starving(rdp, &j)) - return; - - pr_err("%s kthread starved for %ld jiffies\n", rcuc->comm, j); - sched_show_task(rcuc); - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); -} - /* Complain about starvation of grace-period kthread. */ static void rcu_check_gp_kthread_starvation(void) { @@ -662,9 +658,6 @@ static void print_cpu_stall(unsigned long gps) rcu_check_gp_kthread_expired_fqs_timer(); rcu_check_gp_kthread_starvation(); - if (!use_softirq) - rcuc_kthread_dump(rdp); - rcu_dump_cpu_stacks(); raw_spin_lock_irqsave_rcu_node(rnp, flags);